A modulator/demodulator (“modem”) may be used to communicate digital signals over an analog network, such as the Public Switched Telephone Network (PSTN), for example. A modem may be implemented in hardware or software. Software modems are typically executed by a processing system such as a computer, and may therefore be subject to the performance constraints of the processing system. Consequently, software modems may not provide the same set of functionality as a hardware modem. Accordingly, there may be a need for improvements in software modems.